The synthetic low radioactive wastewater containing Cs+ was treated by a four-chamber electrodeionization process at constant current. Effects of various operation parameters including electrical current, feed flow rate, the initial concentration and pH value, and the volume reduction factor are investigated respectively. The optimum variables are as follows: the electrical current is 0.14 A, the feed flow rate is 6.0 L h(-1), the initial Cs+ concentration is less than 50 mg L-1, the initial feed pH is 7.0, and the volume reduction factor is lower than 40. Under these conditions, the effluent Cs+ concentration in the dilute chamber is below 0.05 mg L-1, and the removal percentage of Cs+ can be achieved to be 99.9%. (C) 2014 Elsevier B.V. All rights reserved.